Performance info on Volvo diesels in Bertram 25

[nestorpr]

Hi guys, for those of you who may be interested: an owner of a Bertram 25 Flybridge Cruiser just installed a pair of Volvo D3-160 diesel outdrives in his boat and reports a top speed of about 40 knots and a cruise of around 30. Fuel consumption? 1.2 gph per engine at cruise! Not bad for an almost 7,000 lb boat! Something to think about when repowering. Go to 25Bertram.com for details.

[Briguy]

That's a bunch of crap. No 160hp diesel burns 1.6gph at cruise. Do a simple calculation of rated hp x 3% and you will get pretty close to gph at cruise on a diesel. For a 4 stroke ob or ib use rated hp x 5%.

160hp x 3% =4.8gph each or 10gph total at 30 mph he nets 3mpg. Using his gph numbers he is burning total of 3.2gph at 30 mph for a net of 9.37 mpg.

PS at WOT diesels burn about 5% of rated hp and carbed 2 stroke outboards burn about 10% of rated hp at wot.

Also calling bs on 40kt top. That's my rant for the day!

I also know this because Mastry Marine in Tampa ran a test on a 23 seacraft with a 4cyl yanmar 230 and a bravo 3 and it burned between 6-7 1/2 gph at cruise netting about 3.2 to 3.8 mpg. FYI top speed was 38kts. For $23,000 installed it was out of my price range so I went with twin 4 strokes and net 3mpg at 25.5 kts. The diesel did not present big enough diffenence for me.

[nestorpr]

Hey, I was just passing on the numbers for those that may be interested in this new technology diesel. However, the owner is using the Volvo flow meters and gps that came with the engines so perhaps they're not properly calibrated. I know the G-man also installed this engine in his Bertram 20 and got a less than 3 mpg at 30 mph reading on Flowscan instruments which kind of follows your math.

Bear also in mind that the Yanmars weigh about 219 lbs each more than the Volvos (Yanmar 160 hp 4LHA-HTP engine 794 lbs, Mercruiser Bravo X Diesel drive 141 lbs, total 935 lbs each. Volvo 160 hp D3-160 engine/SX outdrive 716 lbs each complete) so perhaps that's the difference between your math and the G-man's results. Anyway I'm not a mechanical engineer and this is not my boat so I won't pretend to know. Like I said, I just passed this info on in case someone was interested they could check them out with their dealer. BTW, a dealer in Miami quoted me $17,000 for the Volvo 190 hp D3-190 so I don't think they're so unreasonable compared to outboards, and I agree, $23,000 is a lot of money for any engine.